Squall and Rinoa implied.
Irvine and Selphie implied.
What for Seifer?

Seifer´s ROMANTIC dream was to be the sorceress knight.
I can´t see how can he do anything good to Rinoa being Edea´s knight.
And for U=R believers I must say that Seifer didn´t knew anything about Ulti on the first disc.
Considering how he fight for the sorceress I must say that he loves Edea.
I also believe that Zell and Quistis were married before Hyne created WOTC and put Quistis as an instructor.
Thus the approximation between Squall and Quistis is explained.Squall is a talented student.Zell is a less rank student.The approximation between Quistis and Squall is more probable.Also the approximation between Zell and the librarian is more probable.
That´s Hyne´s plan.That way Hyne can also freeze the relationship between Squall and Rinoa.
If you think about it you will see that at the beggining of the game our characters were on a position which prevents them to relate with they mate.For instance.

Rinoa was separated from Squall on the orphanage.
Selphie and Irvine were scattered to two distant Gardens.
Hyne don´t really knew that Martine(Laguna) would just put Irvine with our characters.
At least he hoped not.
Seifer was separate from Edea.
And finally Zell were with Quistis but with very different Garden positions.